Karyotype Test: How It Is Done

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How It Is Done

Karyotype testing can be done using almost any cell or tissue from the body. A karyotype test usually is done on a blood sample taken from a vein. For testing during pregnancy, it may also be done on a sample of amniotic fluid or the placenta.

Blood sample from a vein

The health professional drawing your blood will:

• Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
• Clean the needle site with alcohol.
• Put the needle into the vein. More than one needle stick may be needed.
• Attach a tube to the needle to fill it with blood.
• Remove the band from your arm when enough blood is collected.
• Apply a gauze pad or cotton ball over the needle site as the needle is removed.
• Apply pressure to the site and then a bandage.

Cell sample from a fetus

For this type of test, cells are collected from the fetus using amniocentesis or chorionic villus sampling. For more information about amniocentesis, see the medical test Amniocentesis or Chorionic Villus Sampling.

Cell sample from bone marrow

Bone marrow aspiration may be used for a karyotype test. For more information about how this test is done, see the medical test Bone Marrow Aspiration and Biopsy.

Last updated:	April 26, 2007
Author:	Maria G. Essig, MS, ELS
Reviewed By:	Joy Melnikow, MD, MPH - Family Medicine, Renee H. Martin, PhD - Medical Genetics
Editors:	Susan Van Houten, RN, BSN, MBA, Tracy Landauer